The present invention relates to small arms ammunition and, more particularly, to a hollow-point projectile designed for an auto-loading pistol.
Recently, several law enforcement agencies, including the Law Enforcement Assistance Administration (L.E.A.A.) have developed criteria for the selection of handgun ammunition for use by law enforcement officers. In general, the criteria are: maximum muzzle energy, optimum penetration, minimum weight loss or fragmentation upon upset, and acceptable pressure loading, accuracy and reliability.
Optimum penetration is defined as six inches or less in tissue simulating gelatin. This limitation was adopted to protect bystanders who might otherwise be injured by a projectile passing through the intended target and further serves to insure that all the projectile energy is transferred to the target and that the bullet ends up in one piece in the target and can be recovered for use as evidence. High rates of energy transfer, coupled with a high muzzle energy, are desirable to instantaneously disable the target, thereby preventing return fire on the law officers and eliminating the need for further fire on the target.
High energy transfer commonly called "punch" or "knock-down power", coupled with controlled or limited projectile penetration, is conventionally achieved by use of a "hollow point" configuration wherein a centrally disposed axially directed recess is provided in the projectile nose. Such a recess weakens the projectile nose structurally and provides outward forces in the recess since target material flowing into the recess as the bullet penetrates the target has nowhere to go but material flowing past the tip is largely unrestricted such that, upon impact, an unjacketed lead projectile "mushrooms," opening outwardly and backwardly, thereby presenting a greatly increased frontal area.
Reliability of auto-loading pistol and revolver ammunition is measured in terms of uniformly predictable successful functioning in an auto-loading pistol, a type of weapon being adopted by an increasing number of law enforcement agencies for increased fire power and ease of operation.
To insure proper feeding, and prevent "jamming," the projectiles, generally formed of lead or a soft lead alloy, must resist deformation, especially deformation of the projectile nose, prior to firing. Deformation resistance is presently achieved through the provision of a protective covering or jacket, generally of brass or, less frequently, steel.
Unfortunately, the jackets of many of the presently available fully jacketed auto-loading ammunition, while preventing deformation prior to firing, also prevent the desired mushrooming upon impact. This may result in the projectile passing completely through the target and being lost as evidence and not achieving the desired instantaneous disablement. A bystander may then be injured by the projectile, either by being in the path of the bullet as it exits the initial target, or by a ricochet off a hard object such as a building or automobile.
This problem becomes particularly acute in bullets for the lower velocity (e.g. less than about 950 feet per second muzzle velocity) pistols and revolvers such as snubnosed 0.38 specials, 0.380 Auto caliber and 0.45 Auto and Long Colt caliber handguns being increasingly used by undercover or plainclothes policemen, where the short barrel lengths do not give sufficient impact velocity (greater than about 950 f.p.s.) to produce upset or mushrooming of present aluminum jacketed bullets loaded to maximum safe pressure levels.
Attempts at promoting mushrooming of a jacketed, hollow point projectile have generally involved internal or external scoring, slitting or otherwise weakening the fully formed jacket in the area of the projectile nose. For example, U.S. Pat. Nos. 2,765,738 and 2,838,000 show internal jacket scoring methods while U.S. Pat. No. 3,349,711 shows external scoring of a copper plated rifle varmint bullet designed to fragment. Projectiles of this type have not been believed to be satisfactory for police use since the degree of expansion and depth of penetration are highly dependent on the projectile's velocity at the point of impact and also on the uniformity among projectiles of the method used to weaken the jacket material. Specifically, I have found that upon impact at such low velocities (less than about 950 f.p.s.) brass or copper-jacketed hollow point projectiles would not expand whether notched or unnotched, thereby allowing them to pass through the target. To the layman this seems crazy as one would not expect that the slower the bullet travels the more likely the bullet is to pass through the victim. But, with soft-point ammunition that is the case since bullet expansion does not occur.
One particularly successful solution to the need for reliable mushrooming for muzzle velocities in the range of 950-1,200 f.p.s. is that disclosed in U.S. Pat. No. 4,193,384, namely, a purposefully unnotched jacket having a sufficient hardness (between about 45 and 60 as measured by the Rockwell R-15T Hardness Tester) and shear strength (between about 12,000 and about 24,000 p.s.i.) so that it would not foul the gun barrel but yet would allow upset to occur.
However, there is a need to attain this mushrooming effect with low muzzle velocity (&lt;950 f.p.s.) pistols and revolvers for which such has been heretofor unsuccessful.
There is, thus, a need for a more dependable expanding bullet for low muzzle velocity pistols such as snub nosed (e.g. 2" barrels) pistols in order to allow for reduced weight, easier handling pistols.